Bore
Cylinder bore diameter
Read full guideAbbreviation · full form · practical meaning · selection impact
Decode pneumatic terminology in the context that matters.
Search technical terms used in product catalogs, circuit diagrams, RFQs, replacement projects, and machine-maintenance discussions.
55working definitions
8selection categories
4 fields: term, meaning, use, and caution
Detailed selection guides
Start with high-impact terms
These terms frequently change cylinder force, valve capacity, air quality, circuit behavior, or connection compatibility. Open a guide for the calculation basis, selection checks, common mistakes, and technical references.
Stroke
Cylinder travel
Read full guideA
Effective piston area
Read full guideΔP
Pressure drop
Read full guideCv
U.S. flow coefficient
Read full guideC
Sonic conductance
Read full guide5/2 valve
Five-port, two-position valve
Read full guideFRL
Filter, regulator, lubricator
Read full guidePDP
Pressure dew point
Read full guideNPT
National Pipe Taper thread
Read full guideCategory
This glossary explains each pneumatic term through its full form, practical meaning, and the product-selection decision it may affect.
- ACylinder sizingFull form
Effective piston area
Practical meaningPressurized piston area used in the theoretical force calculation.
Why it affects selectionUse the rod-side annular area for retract force, not the full bore area.
- BoreCylinder sizingFull form
Cylinder bore diameter
Practical meaningInside diameter associated with piston area.
Why it affects selectionForce rises with the square of bore diameter.
- StrokeCylinder sizingFull form
Cylinder travel
Practical meaningDistance between the retracted and extended end positions.
Why it affects selectionConfirm usable motion, overall length, and allowance for cushioning.
- DACylinder sizingFull form
Double acting
Practical meaningAir pressure powers both extension and retraction.
Why it affects selectionRequires directional control and consumes air in both directions.
- SACylinder sizingFull form
Single acting
Practical meaningAir powers one direction and a spring or external load returns the actuator.
Why it affects selectionCheck spring force, fail position, and usable stroke.
- CushioningCylinder sizingFull form
End-of-stroke cushioning
Practical meaningA method of reducing piston speed near an end cap.
Why it affects selectionMatch kinetic energy and cycle speed; cushioning does not replace external stopping when limits are exceeded.
- Proof pressurePressure & safetyFull form
Proof test pressure
Practical meaningPressure used to verify integrity without permanent deformation under stated conditions.
Why it affects selectionIt is not the normal operating-pressure rating.
- Burst pressurePressure & safetyFull form
Failure pressure
Practical meaningPressure at which a component may rupture or lose containment.
Why it affects selectionNever use it as a working-pressure target.
- MAWPPressure & safetyFull form
Maximum allowable working pressure
Practical meaningHighest permitted working pressure under specified conditions.
Why it affects selectionUse the lowest rating of every component in the circuit.
- PabsPressure & safetyFull form
Absolute pressure
Practical meaningPressure referenced to a perfect vacuum.
Why it affects selectionRequired in gas-law and vacuum calculations.
- PgPressure & safetyFull form
Gauge pressure
Practical meaningPressure referenced to local atmospheric pressure.
Why it affects selectionDo not mix gauge and absolute values in one formula.
- ΔPFlow & valvesFull form
Pressure drop
Practical meaningDifference between upstream and downstream pressure.
Why it affects selectionAvailable valve and line flow changes with pressure drop.
- CvFlow & valvesFull form
U.S. flow coefficient
Practical meaningA conventional coefficient describing flow capacity under a defined test basis.
Why it affects selectionDo not compare it directly with nominal NL/min without the fluid state and test conditions.
- KvFlow & valvesFull form
Metric flow coefficient
Practical meaningMetric coefficient convention commonly used for valve flow capacity.
Why it affects selectionCv and Kv are related conventions but are not numerically identical.
- CFlow & valvesFull form
Sonic conductance
Practical meaningISO 6358 flow characteristic representing conductance in choked flow.
Why it affects selectionUse with critical pressure ratio and absolute pressure conditions.
- bFlow & valvesFull form
Critical pressure ratio
Practical meaningISO 6358 ratio marking transition between choked and subsonic flow behavior.
Why it affects selectionNeeded with sonic conductance for standardized pneumatic flow calculations.
- Choked flowFlow & valvesFull form
Sonic flow
Practical meaningCondition where mass flow no longer increases by lowering downstream pressure at fixed upstream conditions.
Why it affects selectionIncreasing component conductance or upstream pressure may be needed for more flow.
- SCFMFlow & valvesFull form
Standard cubic feet per minute
Practical meaningVolumetric flow referenced to stated standard conditions.
Why it affects selectionAlways confirm the reference temperature, pressure, and humidity convention.
- NL/minFlow & valvesFull form
Normal litres per minute
Practical meaningVolumetric flow normalized to a stated reference condition.
Why it affects selectionNormal conditions vary by convention; record the supplier basis.
- ANRFlow & valvesFull form
Atmosphère Normale de Référence
Practical meaningReference-air condition used by some pneumatic catalogs for normalized flow.
Why it affects selectionKeep ANR values tied to the catalog's stated reference definition.
- QnFlow & valvesFull form
Nominal or normalized flow rate
Practical meaningCatalog flow value defined under a stated test condition.
Why it affects selectionCompare only when pressure conditions and measurement conventions match.
- 3/2 valveValves & circuitsFull form
Three-port, two-position valve
Practical meaningDirectional valve with three ports and two switching states.
Why it affects selectionCommon for single-acting actuators and on/off air functions.
- 5/2 valveValves & circuitsFull form
Five-port, two-position valve
Practical meaningDirectional valve with pressure, two working, and two exhaust ports.
Why it affects selectionCommon for double-acting cylinders.
- 5/3 valveValves & circuitsFull form
Five-port, three-position valve
Practical meaningDirectional valve with a defined center state.
Why it affects selectionSpecify closed, pressure, or exhaust center; center function changes actuator behavior.
- NCValves & circuitsFull form
Normally closed
Practical meaningFlow path is closed in the defined normal or de-energized condition.
Why it affects selectionConfirm which ports the catalog calls normally closed.
- NOValves & circuitsFull form
Normally open
Practical meaningFlow path is open in the defined normal or de-energized condition.
Why it affects selectionUse when the required fail-state needs flow.
- Pilot operatedValves & circuitsFull form
Pilot-actuated valve
Practical meaningMain element is shifted using pilot pressure.
Why it affects selectionCheck minimum pilot or differential pressure.
- Direct actingValves & circuitsFull form
Direct-actuated valve
Practical meaningSolenoid or mechanical input acts directly on the sealing element.
Why it affects selectionUseful where zero differential operation matters, usually with lower maximum flow.
- SpoolValves & circuitsFull form
Sliding valve element
Practical meaningInternal element routes air between valve ports by moving along a bore.
Why it affects selectionLeakage, overlap, and contamination tolerance affect application behavior.
- PoppetValves & circuitsFull form
Seat-type valve element
Practical meaningSealing element opens away from a seat.
Why it affects selectionOften offers short travel and tight shutoff; verify required actuation force.
- QEVValves & circuitsFull form
Quick exhaust valve
Practical meaningExhausts cylinder air locally instead of returning it through the directional valve.
Why it affects selectionCan increase speed but changes exhaust noise and motion control.
- Meter-outValves & circuitsFull form
Exhaust-flow control
Practical meaningRestricts air leaving an actuator.
Why it affects selectionPreferred for stable control of many pneumatic cylinder loads.
- Meter-inValves & circuitsFull form
Supply-flow control
Practical meaningRestricts air entering an actuator.
Why it affects selectionUse selectively because overrunning loads can become unstable.
- FRLAir preparationFull form
Filter, regulator, lubricator
Practical meaningCombined compressed-air preparation assembly.
Why it affects selectionSelect filtration, pressure range, drain, bowl, flow, and lubrication based on the application.
- PDPAir preparationFull form
Pressure dew point
Practical meaningTemperature at which water vapor condenses at the stated pressure.
Why it affects selectionChoose dryer performance below the lowest relevant system temperature.
- ISO classAir preparationFull form
ISO 8573-1 purity class
Practical meaningThree-part compressed-air cleanliness statement for particles, water, and oil.
Why it affects selectionSpecify every position and the measurement point.
- DroopAir preparationFull form
Regulator pressure droop
Practical meaningReduction in downstream pressure as flow demand increases.
Why it affects selectionSize the regulator from its flow curve, not port size alone.
- Cracking pressurePressure & safetyFull form
Initial opening pressure
Practical meaningDifferential pressure at which a check or relief element begins to open.
Why it affects selectionIt affects low-pressure operation and retained pressure.
- HysteresisMeasurement & controlFull form
Directional response difference
Practical meaningDifference in output depending on whether the input approaches from above or below.
Why it affects selectionRelevant to regulators, sensors, proportional devices, and repeatability.
- RepeatabilityMeasurement & controlFull form
Repeat output consistency
Practical meaningCloseness of repeated results under the same conditions.
Why it affects selectionDo not confuse it with absolute accuracy.
- Response timeMeasurement & controlFull form
Actuation response interval
Practical meaningTime between an input change and a defined output response.
Why it affects selectionInclude valve, tubing, load, pressure, and sensor delays in cycle estimates.
- FRAir preparationFull form
Filter regulator
Practical meaningCombined particulate filter and pressure regulator.
Why it affects selectionConfirm drain type, filtration rating, relieving function, and flow curve.
- Vacuum levelVacuumFull form
Pressure below atmosphere
Practical meaningMagnitude of sub-atmospheric pressure stated as gauge vacuum or absolute pressure.
Why it affects selectionRecord the reference and unit; percentages of vacuum can hide assumptions.
- kPa absVacuumFull form
Kilopascals absolute
Practical meaningAbsolute-pressure unit commonly used for vacuum work.
Why it affects selectionLower absolute pressure means a stronger vacuum.
- Holding forceVacuumFull form
Vacuum-cup holding force
Practical meaningIdeal pressure-difference force over effective cup area before losses and safety factors.
Why it affects selectionDerate for acceleration, orientation, leakage, surface texture, and cup geometry.
- Safety factorVacuumFull form
Design factor
Practical meaningMultiplier between calculated minimum and selected capacity.
Why it affects selectionChoose it from motion, surface, failure consequence, and application guidance.
- Leak rateVacuumFull form
Air or vacuum leakage rate
Practical meaningRate at which gas enters or escapes a system under stated conditions.
Why it affects selectionIt sets pump/ejector demand and pressure retention time.
- NPTThreads & connectionsFull form
National Pipe Taper thread
Practical meaningTapered inch pipe-thread system widely used in North America.
Why it affects selectionDo not mate it with BSPT solely because nominal sizes appear similar.
- BSPP / GThreads & connectionsFull form
British Standard Pipe Parallel thread
Practical meaningParallel pipe thread commonly identified by G.
Why it affects selectionSealing normally occurs with an O-ring, washer, or bonded seal, not on the thread flank.
- BSPT / RThreads & connectionsFull form
British Standard Pipe Taper thread
Practical meaningTapered external pipe thread commonly identified by R.
Why it affects selectionConfirm the matching internal thread form, such as Rp or Rc, and seal method.
- RcThreads & connectionsFull form
Tapered internal pipe thread
Practical meaningBSP-family tapered female thread designation.
Why it affects selectionVerify pairing and sealing practice rather than relying on nominal size.
- Tube ODThreads & connectionsFull form
Tube outside diameter
Practical meaningOutside diameter used to size most push-in pneumatic fittings.
Why it affects selectionMetric and inch tube sizes are not interchangeable even when close.
- Push-in fittingThreads & connectionsFull form
Push-to-connect fitting
Practical meaningCollet-and-seal tube connection installed by pushing prepared tube into the fitting.
Why it affects selectionMatch tube material, OD, pressure, temperature, and release clearance.
- ManifoldValves & circuitsFull form
Common valve or distribution base
Practical meaningBase that shares supply and exhaust or distributes ports among multiple stations.
Why it affects selectionConfirm station pitch, electrical architecture, total flow, and expansion limits.
- SilencerValves & circuitsFull form
Pneumatic exhaust muffler
Practical meaningPorous or baffled element used to reduce exhaust noise.
Why it affects selectionBackpressure can reduce cylinder speed and valve performance.
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Before reusing a catalog value, verify the abbreviation, reference condition, unit, and manufacturer or standard context.
How can you move from a pneumatic term to an engineering check?
Use the calculator library for preliminary sizing, or send the complete product and application details for drawing support.